ASTM D1957 Standard Test Method for Hydroxyl Value of Fatty Oils and Acids
4. Apparatus
4.1 Erlenmeyer Flask, 250-mL, standard ground-glass-stoppered.
4.2 Condensers, straight-tube, Liebig type, having standard ground-glass joints.
5. Reagents
5.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents shall conform to the Specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. Other grades may be used provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
5.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to Type I of Specification D1193.
5.3 Acetic Anhydride, (Warning - See 6.5) fresh.
5.4 n-Butyl Alcohol (Warning - See 6.1), neutralized with 0.5 Nalcoholic potassium hydroxide (KOH) solution to a faint pink phenolphthalein end point.
5.5 Ethyl Alcohol or Denatured Alcohol, conforming to Formula No. 3A or 30 of the U. S. Bureau of Alcohol, Tobacco, and Firearms. Formula No. 3A is a mixture of 100 parts by volume of ethanol to 5 parts by volume of methanol. Formula 30 is 100 parts by volume of ethanol and 10 parts by volume of methanol.
5.6 Phenolphthalein Indicator Solution (10 g/L) - Dissolve 1 g of phenolphthalein in methanol, ethanol, or isopropanol, and dilute to 100 mL.
5.7 Potassium Hydroxide, Alcoholic Solution (0.5 N) (Warning - See 6.3) - Prepare and standardize a 0.5 N solution of potassium hydroxide (KOH) in ethanol. The strength should be not less than 0.5 N in order that the blank titrations will take less than 50 mL to avoid refilling the buret.
5.8 Pyridine (Warning - See 6.4), distilled at 114 to 115°C.
5.9 Pyridine-Acetic Anhydride Solution (3 + 1) - Mix 3 volumes of pyridine with 1 volume of acetic anhydride. Prepare fresh before using.
6. Hazards
6.1 n-Butyl Alcohol is a flammable liquid. The liquid and vapor are irritants to the eyes, skin and mucous membranes. Use with adequate ventilation (hood), (TLV-100 PPM). See supplier's Material Safety Data Sheet.
6.2 Ethyl Alcohol (denatured) is a flammable liquid. Liquid and vapor are harmful, the severity depending upon the concentration of the alcohol and the nature and concentration of the denaturant. Do not use denatured alcohol containing benzene. Do not swallow. Avoid breathing vapor and contact with skin and eyes. See supplier's Material Safety Data Sheet.
6.3 Potassium Hydroxide and its strong solutions are caustic to the skin and eyes. Avoid all contact with skin and eyes. Remove contaminated clothing and wash before reuse. See supplier's Material Safety Data Sheet.
6.4 Pyridine is a flammable liquid and hazardous by inhalation. It is an eye, skin, and respiratory irritant (TLV-5 PPM). May cause liver and kidney damage. Use with adequate ventilation; perform all operations in a hood. See supplier's Material Safety Data Sheet.
6.5 Acetic Anhydride is corrosive and may cause burns to the skin and eyes; the vapor is irritating to mucous membranes. Use in a hood. Remove contaminated clothing and wash before reuse. See supplier's Material Safety Data Sheet.
